Existing respiratory nosepieces for gas sampling are typically made by dipping a wire frame into plastisol (a suspension of polyvinyl chloride (PVC) particles). The dipped wireframe is cured by heating, and the cured respiratory nosepiece is then hand-stripped off the wire frame. Such dipping processes are time consuming and expensive, but are however considered necessary to manufacture respiratory nosepieces having the low deadspace (low internal volume) required for gas sampling.
Conventional injection molding techniques generally are not used to manufacture respiratory nosepieces for gas sampling, because the small mold pin dimensions necessary to realize small diameter channels (low internal volume) typically result in resin flash that forms occlusions within the channels. The occlusions create turbulence within the sample gas flow, degrading gas sample signal fidelity.
It would be desirable to provide a low-cost respiratory nosepiece having low internal volume, and an efficient method of manufacturing a respiratory nosepiece that avoids formation of occlusions and maintains gas sample signal fidelity.